The present disclosure relates to a method for calibrating a color space transformation, a method for color space transformation and a color control system for a light source.
Color-tunable light sources have become popular in various lighting applications. In particular, implementations using light-emitting diodes, LED, based light sources offer a whole range of possible features for lighting applications. Such color-tuneable light sources are, for example, used in ambient lighting applications or backlighting applications for dashboards in automotive products. Another application is color-tuneable backlights for displays. In the field of general lighting applications particularly white tuneable light sources play a major role. LED-based solutions allow for a tuning of the white point, in particular by adjusting the correlated color temperature of the emitted light. In general, such lighting applications feature high requirements on color accuracy and maintenance. For example, luminary to luminary matching is necessary in order to prevent the human eye from perceiving the color of light from different luminaires differently. In particular, with respect to changing ambient temperatures, different light intensities and in view of the long lifetime of LED-based light sources color accuracy and maintenance may be crucial.
In this context, commonly color space transformations, in particular from an RGB color space to an XYZ color space, are involved when measuring or controlling color deviations or differences. On the one hand this is due to the fact that the measurement of color coordinates is technically favourable in an RGB color space, for example the CIE 1931 RGB color space. However, for applications where the perception of an observer is of relevance, expressing color differences makes most sense in a color space adjusted to the biological principles of human color reception, such as an XYZ color space, for example the standard observer CIE 1931 XYZ color space.